Questions tagged [template-aliases]
67 questions
6
votes
2 answers
Using boost::shared_ptr with a view to replacing it later
I am working on cross-platform code that needs shared pointers. For reasons beyond my control we cannot use C++11 just yet. So, I have suggested using boost::shared_ptr. When we do adopt C++11 (maybe a year down the line), we should be able to…
341008
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5
votes
2 answers
C++ 11 conditional template alias to function
In C++ 11, I want to make a template alias with two specializations that resolve to a different function each.
void functionA();
void functionB();
template
using Loc_snprintf = functionA;
template<>
using Loc_snprintf =…
Adrián
- 45
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5
votes
1 answer
Why can't GCC compiler deduce one of the template parameter from std::array in alias template form
In C++20, alias templates can have implicit deduction guides if it is applied.
Then, I have constructed a simple template alias which is ints:
template
using ints = std::array;
but:
ints{1, 2, 3, 4}
doesn't work, and GCC…
Desmond Gold
- 1,517
- 1
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5
votes
1 answer
Strange behaviour of is_same_template on template aliases
The following program...
#include
#include
template
struct Template{};
template
using Alias = Template;
template
<
template
class T1,
template…
Constructor
- 7,273
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- 66
5
votes
1 answer
Can type to value meta-function be used as variable alias in C++14?
While looking at C++14 the meta-function alias proposals (TransformationTraits Redux, v2,N3655), I noticed that, not only type to type transformations (such as add_const), type to value meta-functions (such as is_void ) are also type aliased. (Which…
abir
- 1,797
- 14
- 26
4
votes
3 answers
Why a template alias specialization depends on the context in which it is referred?
Consider this example code:
template
using pt_type = typename T::type;
template
class V {
using type = int;
public:
using pt = pt_type;
};
void g() {
V::pt a; // Does compile
pt_type> b; // Does not…
Oliv
- 17,610
- 1
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- 72
4
votes
0 answers
Is templated alias conducting inner and outer parameter packs non-deduced context?
The problem came from here - I wanted to create an approach solving a little bit more general problem. Consider an example:
#include
template
using deduced = T;
template
W.F.
- 13,888
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- 81
4
votes
3 answers
Best way (Or workaround) to specialize a template alias
I'm currently implementing a tiny metaprogramming-based compile-time computations library.
If have defined a base class for operators, which has a result typedef (I have decided to use integral wrappers like std::integral_constant as values instead…
Manu343726
- 13,969
- 4
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- 75
4
votes
1 answer
Template alias not working in argument of template class template method
When I declare a template method of a template class whose argument type is specified by a template alias, I get a compile error. If I change the template class to a class, it compiles. If I replace the template alias by the actual type (here…
user2360448
- 63
- 2
- 5
3
votes
1 answer
Template aliases don't work
I'm trying to get template aliases to work on clang but it doesn't work although the reference sheet says it does
~~~~>$ cat template_alias.cpp
#include
using namespace std;
template
using DoubleVec = vector>;
int…
Daniel
- 30,896
- 18
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3
votes
0 answers
Alias to dependent type only allows class types on GCC 12, but allows fundamental types on most other compilers
I found that the code snippet below compiles fine on gcc 11, clang, and MSVC, but starting with gcc 12.1, it gives the error:
using Y = typename Derived::template X<1>; // offending line
error: 'class Derived::X<1>' resolves to…
gchen
- 126
- 6
3
votes
2 answers
How to create alias for template type?
I have some template classes whose declaration looks like this:
template
class foo1;
template
class foo2;
...
I use them in the following context…
Igor
- 1,307
- 1
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- 19
3
votes
2 answers
template alias for function with varying number of arguments
I have a class template Foo which has several members, one of which is a function bar of type Bar:
template
class Foo
{
...
Bar bar;
...
};
I would like Bar<2> to be a template alias for a function double (* )(double,…
JorenV
- 373
- 2
- 10
3
votes
2 answers
Template alias scope
As per http://en.cppreference.com/w/cpp/language/type_alias, aliases are block-level declarations. It doesn't say anything special about template aliases, so it should be read that template aliases are block-level declarations as well.
However, it…
SergeyA
- 61,605
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- 137
3
votes
1 answer
C++ dynamic downcasting to class template having template template parameter being a class template or an alias template
I hope the title makes sense. I probably miss vocabulary to express it correctly.
Well, an exemple will probably be more clear.
Problem for me is: dynamic downcasting returns 0 at run time in some of the following cases (written in comments). I'd…
brahmin
- 568
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